Exercise: reverse a string

Write a function func reverse(s string) string that returns the characters of the string s in reverse order.

• reverse("hello") → "olleh"
• reverse("Привет") → "тевирП"
• reverse("Go, мир") → "рим ,oG"

Constraints: the string is non-empty, up to 100 characters; it may contain Cyrillic, accented Latin letters, digits, spaces and punctuation.

Do not add extra imports unless the task says so explicitly.